Engine driven flywheels have been long recognized as energy dense sources from which mechanical work may be derived. Demands on flywheels have become increasingly greater as engines and prime mover systems have become larger and more powerful. As such, flywheels and their associated elements have tended to evolve into larger, more massive structures. Such structures have become commensurately more expensive. Thus, there has been considerable pressure to reduce costs of flywheel systems.
One approach has been to utilize more efficient flywheels, including flywheels adapted to rotate at considerably higher speeds within vacuum housings. While this approach has been determined effective to produce greater amounts of energy from single flywheel units, there remains a demand for the use of even greater amounts of energy storage and use, particularly with increasingly greater requirements of large off-highway machines.